The present invention generally relates to drug delivery devices, and more specifically relates to disposable, pre-fillable drug cartridge for use with a reusable body portion of an injection device for injecting drugs or medicaments into patients which are commonly known in the field as pens.
Hypodermic syringes are used to deliver selected doses of medication to patients. The prior hypodermic syringe includes a syringe barrel having opposed proximal and distal ends. A cylindrical chamber wall extends between the ends and defines a fluid receiving chamber. The proximal end of the syringe barrel is substantially open and receives a plunger in sliding fluid tight engagement. The distal end of the syringe barrel includes a passage communicating with the chamber. A needle cannula may be mounted to the distal end of the syringe barrel, such that the lumen of the needle cannula communicates with the passage and the chamber of the syringe barrel. Movement of the plunger in a proximal direction draws fluid through the lumen of the needle cannula and into the chamber. Movement of the plunger in a proximal-to-distal direction urges fluid from the chamber and through the lumen of the needle cannula.
Medication to be injected with the prior hypodermic syringe often is stored in a vial having a pierceable elastomeric seal. Medication in the vial is accessed by piercing the elastomeric seal with the needle cannula. A selected dose of the medication may be drawn into the chamber of the syringe barrel by moving the plunger a selected distance in a proximal direction. The needle cannula may be withdrawn from the vial, and the medication may be injected into a patient by moving the plunger in a distal direction.
Some medication, such as insulin is self-administered. The typical diabetes patient will require injections of insulin several times during the course of a week or day. The required dose of insulin will vary from patient to patient, and for each patient may vary during the course of the day and from day to day. Usually, each diabetes patient will establish a regimen that is appropriate for his or her own medical condition and for his or her lifestyle. The regimen typically includes some combination of a slow or medium acting insulin and a faster acting insulin. Each of these regimens may require the diabetes patient to periodically self-administer insulin in public locations, such as places of employment or restaurants. The required manipulation of the standard hypodermic syringe and vial can be inconvenient and embarrassing in these public environments. Examples of syringes are described in U.S. Pat. Nos. 5,250,037 (Bitdinger) and 5,667,495 (Bitdinger), and an example of a filler for mixing insulins is described in U.S. Pat. No. 5,542,760 (Chanoch), the disclosures of which are hereby incorporated by reference in their entirety.
Medication delivery pens have been developed to facilitate the self-administration of medication. An example of one such medication delivery pen is described in U.S. Pat. No. 5,279,585 (Balkwill), which includes a vial holder into which a vial of insulin or other medication may be received, the disclosure of which is hereby incorporated by reference in its entirety. The vial holder is an elongate generally tubular structure with proximal and distal ends. The distal end of the vial holder includes mounting means for engaging a double-ended needle cannula. The proximal end also includes mounting means for engaging a driver and dose setting apparatus as explained further below. A disposable vial for use with the vial holder includes a distal end having a pierceable elastomeric seal that can be pierced by one end of a double-ended needle cannula. The proximal end of this vial includes a plunger slidably disposed in fluid tight engagement with the cylindrical wall of the vial. This medication delivery pen is used by inserting the vial of medication into the vial holder. A pen body then is connected to the proximal end of the vial holder. The pen body includes a dose setting apparatus for designating a dose of medication to be delivered by the pen and a driving apparatus for urging the plunger of the vial distally for a distance corresponding to the selected dose. Other examples of pens are described in U.S. Pat. Nos. 5,645,534 (Chanoch), 5,582,598 (Chanoch) and 5,569,214 (Chanoch), the disclosure of which are hereby incorporated by reference in their entirety.
The user of the pen mounts a double-ended needle cannula to the distal end of the vial holder such that the proximal point cannula of the needle cannula pierces the elastomeric seal on the vial as described, for example, in U.S. Pat. No. 5,549,575 (Giambattista et. al.), the disclosure of which is hereby incorporated by reference in its entirety. The user then selects a dose and operates the pen to urge the plunger distally to deliver the selected dose. The user then removes and discards the needle cannula, and keeps the medication delivery pen in a convenient location for the next required medication administration. The medication in the vial will become exhausted after several such administrations of medication. The user then separates the vial holder from the pen body. The empty vial may then be removed and discarded. A new vial can be inserted into the vial holder, and the vial holder and pen body can be reassembled and used again as explained above.
The above described reusable medication delivery pen is effective and much more convenient for self-administration of medication than the typical hypodermic syringe and separate medication vial. However, it has been found that there is a need for additional features and improvements for such a medication delivery pen. For example, with the increased use of pens for self-injection of drugs other than insulin, there is a need to prevent cross-use of insulin pens with other drugs and/or cross-use of drug cartridges with other pens. The problems associated with cross-use could also pose a potential hazard, where the dose dials of the pens are different, which might result in the administration of the wrong dosage of the drug. This is particularly hazardous where an overdose of insulin could lead to hypoglycemia and ER treatment.
Thus, there has been a need for a pen as well as a drug cartridge assembly, which would eliminate the problems and limitations associated with the prior devices discussed above, most significant of the problems being cross-use of the pen with other drug cartridge assemblies and/or cross-use of the drug cartridge assembly with other pens.
In contrast to the prior devices discussed above, it has been found that a pen particularly suited for use in reducing or otherwise eliminating cross-use can be constructed in accordance with the present invention. Specifically, the pen and the drug cartridge assembly of the present invention are keyed, i.e., they have a connection interface which mechanically prevents the cross-use of cartridge assemblies among designated pens by, for example, using matching threads, bayonets or snap fits on the pen and the holding sleeve of the drug cartridge assembly. Also, the cartridge assembly can have an embedded drug cartridge, not readily separable from each other.
Another object of the present invention is to improve the design of the drug cartridge and holder sleeve so that they are a single integral unit for containing the drug, with a rubber septum for multiple needle penetrations along with a standard thread to attach the pen needle. On the far end of the pen needle thread, a connection interface prevents connection to pens other than the one for which use of the drug container is designed. In this way, the drug cartridge assembly will have minimal dead space and an insert molded rubber septum.